Article révisé par les pairs
Résumé : The results of the Car-Free Sundays in Brussels demonstrate the close relationship between the traffic and the presence of the gaseous pollutants such as NO, NO2, CO, CO2 and O3 in a traffic environment. The relationship with PM10 and PM2.5 seems to be much more complex. In fact, the PM10 andPM2.5 concentrations on the Car-Free Sunday 2006 were amongst the highest that year and they were three times higher than on an average Sunday or working day. Analysis of the data indicate that direct particle emissions from traffic only have a limited contribution to the overall PM concentration. © 2010 Inderscience Enterprises Ltd.